The present invention relates to a shaped article of a polymeric material and its production. More particularly, it relates to a shaped article made of a saturated linear polyester or polyamide having a certain specific structural unit and improved in various physical and chemical properties, and its production.
Saturated linear polyesters and polyamides can be readily shaped in their melt state, and their shaped products are excellent in mechanical properties, heat resistance, chemical resistance, etc. Because of this reason, they are used in various fields, for instance, as fibers, films, etc. Depending on their use, however, their physical or chemical properties are still not satisfactory, and their improvements are desired.
For instance, polyethylene terephthalate as a typical example of saturated linear polyesters is excellent in mechanical properties, heat resistance, dimensional stability, chemical resistance, etc. and used as a starting material for shaped articles such as fibers and films. When, however, heated in air for a long time, the mechanical properties are deteriorated; this is disadvantageous for the use as an electric insulating material, a tire cord or the like. When processed at high temperatures in various steps, the size is more or less changed; this is unfavorable for the use as films, fibers, fabrics, etc. The Young's modulus is still not sufficiently high for the use as a base for magnetic recording tape, a tire cord or the like. Pinhole resistance is poor so that it is not suitable for the use as a packaging film. In case of a biaxially stretched film, the strength in the thickness direction is small, and therefore breakage is easily produced when used as a packaging material, a base for magnetic recording card or the like. On the use as a base for magnetic recording tape, a metallized film or the like, the ligomers tend to move to the surface. These defects are more or less seen also in other saturated linear polyesters and polyamides.
In order to overcome these defects, various proposals including the copolymerization of appropriate monomeric components and the incorporation of suitable resinous materials and/or additives have been made. However, the improvement of some defective properties usually results in the loss of some favorable inherent properties. Thus, the improvement of inferior properties with maintenance of the advantageous inherent properties is generally difficult.